Nothing
Add penalized spline models, so that the 'trend_model' argument may take on "rw" for conventional random walks, "bs" for B-splines, "ps" for "P-splines", or "gp" for Gaussian processes
Change to new Stan syntax
Versioning
Any scripts or data that you put into this service are public.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.